Thousands of passengers have been left furious after British Airways sent an email warning their flights might be cancelled or disrupted due to three days of strikes by pilots.

Weddings, anniversaries and holidays could all be disrupted when flights are grounded on 9, 10 and 27 September.

Some flights scheduled for the days after the industrial action have also been cancelled because of the knock-on effect on crew staffing levels at the company.

The airline’s customer service lines were jammed on Saturday morning after passengers booked on flights had received emails overnight warning of “a large number of delays and cancellations”.

One passenger said his 10-year wedding anniversary “trip of a lifetime” was in doubt after more than 100 calls to BA to get a refund went unanswered.

The walk-outs were announced by the British Airline Pilots Association (Balpa) on Friday night after 93% of its members rejected an 11.5% pay rise across three years.

Scott Kishere, a film-maker and police community officer, said: “My wife and I have been told that our flight to Toronto has been cancelled.

More from British Airways

“This was a full package we booked through BA for our 10-year wedding anniversary. I have made over 100 attempts to contact them for a refund and they’re not answering.

“Until we get a refund we do not have the money to re-book our trip of a lifetime.

“With the days counting down it now looks unlikely we will be able to celebrate our 10-year anniversary as expected.”

Image:The pilots’ union has warned of even more strikes

Mr Kishere, from Dorset, is one of the many passengers who have tried desperately to contact BA on social media and its phone lines.

He is also planning to travel to Chicago for the city’s marathon, with his partner, one week after the final day of strikes, but fears he may not make it.

Mr Kishere said: “We have worked so hard for these trips and BA do not have the decency or customer care to support us.

“For them this has been on the cards for a long time and I cannot believe they didn’t have a contingency in place.”

Chris Deverell, 36, from Bedford, said his “trip of a lifetime” to watch the Rugby World Cup in Japan with his father, which he had spent four years planning, was in doubt.

He said: “At the moment I have not heard anything from BA as to whether it’s going to be cancelled or not.

Image:Passengers were sent emails warning them of disruption

“They have just basically been saying ‘keep checking the website’ and they will email and let us know if it’s going to be cancelled.”

He said they have been able to use air miles to book an alternative flight three days after their planned outbound flight on 27 September but said the threat to the trip was “totally gutting, I’m furious”.

“I’m not going to be able to repeat that experience again,” he said, adding arrangements when he arrived in Japan have also been affected.

“It’s not like a holiday I can do next year, there’s never going to be another Rugby World Cup in Japan in my lifetime.

“The pilots should not be asking for anything more than anybody else.”

A proposed pay deal has been accepted by members of the Unite and GMB unions, which represent engineers, cabin crew and ground staff, according to the airline.

More strike dates could yet be announced, Balpa said, adding they are “a last resort and with enormous frustration at the way the business is now being run”.

Peter Dempsey, 41, fears his family could have to pay hundreds of pounds for alternative flights to return from a family wedding in Seville, southern Spain.

Mr Dempsey, who is due to fly on 5 September for his wife’s cousin’s wedding, said: “It’s the return that has completely screwed us up as we are flying back with our in-laws and we cannot move the dates.

“We have no option but to completely cancel both legs and rebook or they won’t give a refund.”

The replacement flights could cost between £200 and £330 each, compared to the £550 they paid for all four, he said.

Mr Dempsey described the service since the announcement as “shocking”. He added that BA “clearly don’t have enough people to handle such a crisis”.

The airline said it will offer refunds and re-bookings and added: “We will do everything we can to get as many people away on their journeys as possible.”